This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A269621 #8 Jan 25 2019 08:28:03 %S A269621 28,222,954,2956,7440,16218,31822,57624,97956,158230,245058,366372, %T A269621 531544,751506,1038870,1408048,1875372,2459214,3180106,4060860, %U A269621 5126688,6405322,7927134,9725256,11835700,14297478,17152722,20446804,24228456 %N A269621 Number of length-5 0..n arrays with no repeated value differing from the previous repeated value by other than plus two, zero or minus 1. %H A269621 R. H. Hardin, <a href="/A269621/b269621.txt">Table of n, a(n) for n = 1..210</a> %F A269621 Empirical: a(n) = n^5 + 5*n^4 + 7*n^3 + 12*n^2 + 3*n. %F A269621 Conjectures from _Colin Barker_, Jan 25 2019: (Start) %F A269621 G.f.: 2*x*(14 + 27*x + 21*x^2 + x^3 - 3*x^4) / (1 - x)^6. %F A269621 a(n) = 6*a(n-1) - 15*a(n-2) + 20*a(n-3) - 15*a(n-4) + 6*a(n-5) - a(n-6) for n>6. %F A269621 (End) %e A269621 Some solutions for n=8: %e A269621 ..5. .0. .5. .4. .4. .7. .7. .8. .0. .1. .1. .3. .6. .0. .2. .3 %e A269621 ..4. .1. .0. .6. .8. .8. .6. .3. .8. .5. .5. .8. .5. .4. .0. .5 %e A269621 ..5. .2. .7. .5. .3. .0. .0. .4. .6. .3. .6. .0. .7. .5. .4. .4 %e A269621 ..5. .0. .7. .6. .2. .6. .4. .0. .7. .0. .8. .1. .2. .0. .2. .4 %e A269621 ..7. .1. .4. .6. .1. .6. .5. .8. .7. .6. .1. .2. .7. .4. .3. .5 %Y A269621 Row 5 of A269619. %K A269621 nonn %O A269621 1,1 %A A269621 _R. H. Hardin_, Mar 01 2016